Life cycle assessment of a major tropical fruit—sugar apple (Annona squamosa) under different farming systems in Taiwan

Purpose: This study quantifies the environmental impacts of sugar apple production (Annona squamosa) under different farming systems in Taitung, Taiwan, with the inclusion of organically certified materials into the life cycle inventory. It identifies process- and stage-level hotspots, determines the dominant impact category (DIC) for each orchard, and examines how cultivation practices influence yield and environmental performance. These findings aim to inform the strategies that mitigate impacts and align farm management with Taiwan’s sustainability goals. Methods: A cradle-to-orchard-gate life cycle assessment (LCA) was conducted for seven orchards representing conventional, semi-organic, organic, and natural farming systems. Both mass- and area-based functional units (FU_mass, FU_area) were applied, with the inclusion of major organically certified materials (bio-fertilisers, biocontrol agents, and organically certified pesticides) in life cycle inventories. Primary data on yields, inputs, and cultivation practices (2021–2024) were collected via interviews, while upstream processes were modelled using ecoinvent v3.11 within SimaPro v9.6.01. Impact assessment employed the ReCiPe 2016 midpoint method (hierarchist perspective) across 18 impact categories. Hotspot analysis was performed at process and stage levels, and DICs were determined from normalised scores. Agronomic practices were evaluated for their influence on yield and impact rankings, and findings were compared with relevant literature to formulate mitigation recommendations. Results and discussion: Hotspots were mainly associated with fertiliser production and use, packaging material manufacturing, and energy generation. Freshwater eutrophication was the dominant impact in all orchards except N, where human carcinogenic toxicity prevailed. The natural farming orchard consistently showed the lowest impacts due to the absence of fertilisers and pesticides (per kg: N > C4 >C1 >O >C2 >C3 >S; per ha: N > O >C3 >C1 >C4 >S >C2). Under FU_area, the organic system (OS) generally outperformed the conventional system (CS) (CS: 1·11E+00 > OS: 1·04E+00 kg CO₂ eq), whereas under FU_mass, OS exhibited higher impacts in 6 categories. Management practices such as reduced fertiliser application, adoption of organically certified materials, winter double-bagging, mechanical weeding, and optimised crop load improved nutrient-use efficiency and yields, demonstrating their contribution to impact mitigation. Conclusion: This first LCA of sugar apple production in Taiwan shows that systems with low fertiliser input and the adoption of organically certified materials, especially natural farming, provide notable environmental benefits. Functional unit choice influences comparative outcomes, while hotspot and DIC analyses identify fertilisers, pesticides, and packaging materials as key targets for mitigation. These findings support Taiwan’s Organic Agriculture Promotion Plan by demonstrating the potential of reduced fertiliser use and organic material adoption. Future research should incorporate life cycle costing and comprehensive agronomic data to evaluate the economic sustainability of organic practices.